| From | Message |
Jeff
GenIII
5/29/2004
13:44:06
|
 Subject: cb radio vs hu/amp/subs = BOOM!
IP: Logged
Message:
a couple months ago i had a new pioneer hu installed in my pickup truck. also installed two 10" subwoofers and an mtx amp to drive them. amp is (read "should be") grounded to cab floor, and is wired directly to the battery. hu they just hooked up to the factory wires thru a harness/adapter, so i'm not sure about its power/grounding.
i also have a cb radio. my cb is grounded to an in-cab fuse block ground screw. the cb power wire goes to an always-on source in the in-cab fuse block.
the installations, although done by two different people, were both done by professionals. (so no shoddy connections or incorrect wire guage or anything like that)
i recently went on a trip and put the 'ol antenna back on my truck so i could use my cb. here's where it got a little scary. i had the hu on, volume low, and i turned on the cb. when i keyed it (pressed the mic button), the subwoofers did their thing real loud. a big boom. not like an explosion or anything, just like the stereo/amp had sent a signal to do that or something.
i played around with it all and found the following things:
the subs react when i key the cb regardless of hu volume or settings.
the subs do not react when keying if the hu is off (the amp turns off when hu is off as well i believe)
i tried unplugging the rca's from the amp since at the hu end they are close to the cb antenna cable (and i thought maybe picking up rf). still made the noise.
what is going on here?
is the fact that both cb and amp are grounded to the cab causing a problem?
nothing else developed a problem from grounding the amp to the cab (its not like it could be grounded anywhere else anyway unless i run the ground wire out the window)
thanks!
Jeff
'99 3.9 clubcab
|
fy
Dodge Dakota
JOIN HERE
6/16/2004
08:48:22
| RE: cb radio vs hu/amp/subs = BOOM!
IP: Logged
Message:
i have everything that you have in my truck as well. one thing that i would check is the head unit ground. the stock headunit ground wire is not grounded very well. since they used a harness, i would assume the new headunit is using the stock grounding. pull out the headunit and grounded it to the cab.
|
not ground
Dodge Dakota
JOIN HERE
6/22/2004
19:05:53
| RE: cb radio vs hu/amp/subs = BOOM!
IP: Logged
Message:
just a cheap assed but sold as hi end, non off frequency rejecting head unit. it may sound really good but it fails in what is known as "spurious RF rejection" only way to end it is to get a better designed one.
|
Jeff
GenIII
6/24/2004
14:22:26
| RE: cb radio vs hu/amp/subs = BOOM!
IP: Logged
Message:
not ground:
has nothing to do with my head unit. as i already said, i unplugged the hu's rca's from the amp. so unless the cb's signal is going into my hu and Then being transported thru the ground connection to the other end of my cab and up into my amp, its not the hu. or maybe since you say its not the ground, the cb signal is being absorbed by the hu, travelling all around in my dash wiring till it find its way to the battery, Then comes all the way back to the amp. those are the only ways it could have anything to do with the hu, and are ridiculous.
so next time, why don't you read the post before you respond with your arrogant ignorance.
Jeff
'99 3.9 clubcab
|
Brandon K
Dodge Dakota
JOIN HERE
6/24/2004
18:50:43
|  RE: cb radio vs hu/amp/subs = BOOM!
IP: Logged
Message:
Hey Jeff,
I think your problem is just the overwhelming amount of gain from your CB, thats a lot for your amp to handle being as if it's RF power it works kinda crazy. Here's what I would try...
Grounding the outer jacket of your RCA's (I know you said you disconnected them but if you ground them this can help the shielding from interference) I personally think this is a good shot but not likely to fix, since you disconnected the RCA's and it was still doing it.
The next thing would be try placing the antenna somewhere else, maybe on the hood of the vehicle or something further away from the amp.
Last lower the gain on the amp, some amps will create amplify harmonics when the gain is set too high. Your problem might disapear by just loweing the gain.
I had one do this to me before too, but it was before I got into electronics enough to understand it, I had my CB placed on my EQ so the antenna lead was right on the RCA's!!
anyway I hope this was some help let me know how it works out.
|
actually
Dodge Dakota
JOIN HERE
7/17/2004
15:24:30
| RE: cb radio vs hu/amp/subs = BOOM!
IP: Logged
Message:
jeff you little idiot, the amp picks up the signal from the rca jacks as they act like, in this case, a reciever antenna, any wire connected to the jacks acts as an even larger antenna. the signal then feeds thru the amp to the subs, thus the woomp. seen it a thousand times in cheap crap sold as hi end that due to cost cutting bean counters that remove curcuitry that rejects outside "radio frequency" or what is better known as spurious rf rejection. the cb antenna also produces a magnetic field along with the rf signal and the woofers you bought could easily pick up that signal and make a woomp also, especially if you are putting out more then the legal 4 watts by using a "heater" so in conclusion you have cheap crap amp or woofers or both.
|
actually
Dodge Dakota
JOIN HERE
7/17/2004
15:25:01
| RE: cb radio vs hu/amp/subs = BOOM!
IP: Logged
Message:
jeff you little idiot, the amp picks up the signal from the rca jacks as they act like, in this case, a reciever antenna, any wire connected to the jacks acts as an even larger antenna. the signal then feeds thru the amp to the subs, thus the woomp. seen it a thousand times in cheap crap sold as hi end that due to cost cutting bean counters that remove curcuitry that rejects outside "radio frequency" or what is better known as spurious rf rejection. the cb antenna also produces a magnetic field along with the rf signal and the woofers you bought could easily pick up that signal and make a woomp also, especially if you are putting out more then the legal 4 watts by using a "heater" so in conclusion you have cheap crap amp or woofers or both.
|
| | P 1 |
|
Post a reply to this message:
Username Registration: Optional
All visitors are allowed to post messages
|
